A medical device company hoping to move sleep apnea testing out of expensive and uncomfortable labs and into the realm of primary care has gotten a boost from at least 20 investors. Watermark Medical Inc., which recently merged with sleep diagnostics provider SleepMed, has raised $32.2 million since March, according to a SEC filing. An email to the company was not returned. The company manufactures an at-home headset, called ARES, that uses sensors to measure oxygen saturation, pulse, head movement and head position. When that data is combined with responses to questions about a patient’s body type and lifestyle, it could give doctors an indication of the patient’s risk of sleep apnea.